A representation of the Jones vector for laser beam, which comes from a stabilized longitudinal Zeeman laser with frequencies ω 1 and ω 2 and circular left right handed polarizations, and the rigorous formulas of the beat photocurrents for reference beam and signal beam in the heterodyne optical fiber sensor are presented. These formulas cover all informations of phase delay and change of polarization states for these beams caused by all optical elements in the sensing system. Therefore, they can give phase difference formula fitting well with experimental results, and can also be used for explaination of some physical phenomena occured in experiments.